A σ-Donor with a Planar Six-π-Electron B2N2C2 Framework: Anionic N-Heterocyclic Carbene or Heterocyclic Terphenyl Anion?


  • This work was supported by the Natural Sciences and Engineering Research Council of Canada, the Canada Foundation for Innovation, and the Alberta Science and Research Investments Program. K.E.K. thanks the NSERC and the Alberta Ingenuity Fund for doctoral scholarships.


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NB! The anionic ligand 2 was synthesized through deprotonation of a planar, formally zwitterionic diazadiborine precursor, isolated as a lithium salt, and structurally characterized. According to experimental evidence and theoretical calculations, 2 can be considered as an intermediate between two classical classes of ligands: N-heterocyclic carbenes 1 and terphenyls 3.